She has put aside laboratory work for the time being, and is mobilising students, administrating an internet forum on the protests and staffing checkpoints around the Jussieu campus.

Planning

The main entrance is chained and barricaded by a clutter of overturned chairs, rubbish bins and desks. At side entrances, Ms Gombeaud and other students are restricting access to a few chosen activists.

Lelio Stettin, 23, the local leader, currently exerts more authority over the campus than the vice-chancellor, who has so far refrained from calling in the security forces.

So many things need to be done

Lelio Stettin,Student leader

Mr Stettin is a busy man. His phone is ringing constantly.

"So many things need to be done: we have to prepare for another general assembly, leaflets have to be written and printed, we need placards for Tuesday's marches.

"Megaphones, sound systems and vans also have to be arranged. Excuse me, I must take this call."

University staff are also allowed into and out of the grounds - but they are not working. On Monday they were holding their own general assembly to decide whether they would also strike.

A mile away, at the heart of the Latin Quarter, the Sorbonne University too is closed.

But the students are no longer in control - police expelled them after they tried to take over the buildings more than two weeks ago.

Now the capital's flagship university is surrounded by security forces in heavy riot gear. However, Sorbonne annexes on the outskirts of the city are still controlled by striking students.

Merging movements

At one of the sites, in Clignancourt, north of Paris, preparations are going ahead for the forthcoming protests.

"We are working out how, where and when we are all going to meet," says Simon Vacheron, 23, a history student.

Students say the protests have been infiltrated by trouble-makers

One big concern is over security. During previous marches demonstrators have been attacked by troublemakers. Some students have been given the task of protecting others during the rally, Mr Vacheron says.

Violence during the protests has been blamed on various groups - far-right activists, anarchists and sundry outsiders.

But the apparent involvement of some youths from the immigrant suburbs of Paris - who carried out their own uprising last November - divides the current protesters.

"It breaks my heart that thugs are trying to destroy the movement," says Mr Vacheron. "They too are the victims of economic insecurity. The protests are aimed at helping them!"

But others see the current protests and the riots that erupted in France's impoverished suburbs last year as two sides of the same coin.

"The two movements are merging, with blockades taking place in universities in immigrant suburbs."

Choice

Two-thirds of France's universities are being seriously disrupted. French student power has an impressive track record.

I want to study, but students are not being given a choice

Zhor Hocine,Secondary school student

The May 1968 uprisings helped undermine the legitimacy of General Charles de Gaulle, who stood down the following year, and subsequent government plans - notably in 1986, 1994, 1995, and 2005 - were shelved in the face of mass student protests.

This explains why demonstrators are scenting blood. The government has clearly been wrong-footed and blockades have spread to hundreds of secondary schools across the country.

The students have vowed to continue their movement until Prime Minister Dominique de Villepin withdraws the employment plan - known as the CPE.

However not all agree with the blockades.

"I am taking my final exams at the end of the year," says Zhor Hocine, a final year student at the Lycee Rabelais, a blockaded secondary school in northern Paris.

"I want to study, but students are not being given a choice."

Occupations 'illegal'

An active anti-blockade movement has been formed to try to reopen schools and universities.

Sebastien Bordmann, one of the movement's leaders, sees a bitter irony in the fact that many of the current protesters also took to the streets during the 2002 presidential election against far-right candidate Jean-Marie Le Pen.

"They were against the fascists then. Now they are behaving just like them."

Occupations and blockades, Mr Bordmann says, are totally illegal. "Right is on our side," he adds.

For the moment, however, might and numbers are on the side of the protesters - and the anti-CPE coalition is hoping to turn Tuesday's marches and strikes into a decisive show of force.